This proposal describes our pursuit in the ultimate definition of the immunogenetic parameters influencing resistance or susceptibility to collagen induced arthritis (CIA) in mice. The long-term objective of this proposal is to make CIA the best animal model for dissecting the tri-molecular complex in human arthritis. first we will confirm the putative sites on the class II molecules which present type II collagen to autoreactive T cells. Ap and Aq have identical alpha chains and differ only in four residues of the beta chains (85, 86, 88, 89). Yet H-2p is resistant to CIA while H-2q is susceptible. Transgenic mice will be generated with Apbeta mutant gene altered at residues 85, 86, 88 and 89 to simulate Aqbeta. The Apbeta mutant gene will be introduced into the H-2p haplotype to determine whether that changes it to a susceptible haplotype. Studies will involve of type II collagen isolated from human, mouse, chicken, bovine, porcine and rat to determine whether they are all presented by the same or different class II epitopes. Class II negative mice will be used to decipher the role of class II molecules on CIA and whether in the absence of class II other molecules may take over the presentation of antigen. Human HLA, DR 4 beta1 subtypes, DW4, DW10 and DW14 differ only at a few amino acid residues in the alpha helical region. While DW4 and DW14 are linked with RA, DW10 is found to be resistant. We will generate transgenic mice expressing DR4 beta1 subtypes to determine whether they can present type II collagen to generate CIA. Transgenic mice expressing DQw6, DR2 and DR3 have been generated and will be screened for immune response to type II collagen and susceptibility to CIA. The human genes will eventually be transferred into the class II Abbeta negative mice such that they will express only the human class II genes. Antibodies against class II peptides and synthetic class II peptides will be used 'in vivo' to modulate susceptibility to CIA. Major progress was made on the role of T cell receptor Vbeta genes in CIA during the past funding period. T cell receptor Vbeta congenic mice and recombinant mice will be generated to further dissect the T cell receptor Vbeta chains involved in CIA. T cell receptor usage of pathogenic T cells in CIA will be identified and transgenic mice generated with the TCR genes for further analysis. Antibodies against anti-TCR Vbeta chains and synthetic peptides of the variable regions of TCR Vbeta genes will be used in in vivo immunotherapy to modulate CIA. Other background genes involved in CIA will be identified using the microsatellite DNA marker in a backcross segregating population of (DBA/1 x SWR). During this grant period we will concentrate on genes mapping on chromosomes 1, 3 and 11 which code for several interleukin genes. The information gathered from these studies would have far-reaching relevance to ongoing studies on the role of the tri-molecular complex in human arthritis.